Furnace grate



Oct. 7, 1941. M. A. HOFFT ET AL l 2,257,957

FURNACE GRATE Filed Maych 25, 1940 Patented Oct. 7, 1941 UNITED STATES I PAT-ENT. vOFFICE FURNACE GRATE i Maurice A. Hoit and Nick T. Puckett, Indianapolis, Ind.

Application March 25, 194o,seria1-N.325,678

Claims.l y(o1. 122-376) The present invention relates to improvements in furnaces and more particularly to that type of furnaces which are adapted for burning such fuels as refuse, Waste, rubbish, garbage, and like material,v having a high moisture content.

AOne of the objects of the present` invention is to provide a grate for the above type of furnace, which will insure a progressive feed of the material from the intake of the furnace to the back vof the grate, at the same time insuring a proper consumption of the fuel material.

Another object of theV invention is to provide means whereby the grate bars will be prevented from warping under the intense heat developed by the consumption of the fuel and to provide means whereby advantage may be taken of the means for preventing warping of the grate bars for heating Water which may be used for various pllIpOSeS. f

A further object of the invention is to provide means for preventing the grates of the furnace of the above type, from becoming overheated when high temperature preheated air is used, and to prevent the ashand the 'sand which might enter the furnace withthe refuse to be burned, from melting and forming a slag that would stick to the grate.

For the purpose of disclosing the invention an embodiment thereof is illustrated in the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of the furnace having embodied therein our improvements;

Fig. 2 is a plan view of a portion of the furnace grate; and

Fig. 3 is a longitudinal sectional detail View of a portion of the grate.

In the embodiment illustrated, we provide a plurality of water-cooled tubes I which are arranged side by side and extend from the front to the back of the furnace. The tubes are connected at the back of the furnace to a header 2 which extends transversely of the rear portion of the furnace in front of the bridge wall 3 and restS upon suitable supporting brackets 4 secured in the front face of the bridge wall or to the side walls in any desired manner. Further supporting means for the tubes may be provided in the form of a supporting bracket 5 which is carried by the side Wall and extends transversely of the furnace. The upper ends of the tubes I extend through thev front face 'I of the furnace and are connected by suitable separable joint 8 with a transverse header 9. By extending the tubes through the front Wall of the furnace and connecting the same to the header exteriorly of the furnace, we provide an arrangement whereby the header may be removed without entering the furnace and repairs may be made thereto or the tubes themselves cleaned in event they scale.

The upper portion or front portion of the tubes are adapted to be partially embedded in and rest upon a bed I0 of refractory material which may be 'fire clay bricks or a solid bed of lire clay, or any desired material. This bed is supported on top of a suitable supporting plate II, in turn resting upon longitudinally disposed channel or T-bars which in turn are supported upon cross beams I2. The cross beams are, of course, supported from the side walls ofthe furnace. The

`lower end of this plate II and, in fact, the entire refractory bed, rests upon a suitable supporting wall I3 at the inlet end of the fire chamber. Immediately beyond'the refractory bed and extending toward the rear end of the furnace, we provide suitable lgrate bars I4 which are disposed between the tubes I and are removably supported in cross members I5 Welded or otherwise secured to the tubes I.

At the rear end o'f the grate and beyond the grate bars I4, we provide pusher fingers I6 which are supported in trunnions I'I welded to or secured in any suitable manner to the longitudinal water tubes I. These pusher fingers I6 normally lie in the position with'their top surfaces I8 in a at plane. When it is desired to dump the fuel at the rear end of the grate and to break up any clinkers or ashes which may have solidified at the rear end of the grate, the pusher fingers I6 may be tilted upwardly, as shown in Fig. 1, thereby causing the fuel to feed on forward and into the ash pit beyond the header 2 and between the brackets 4.

We have found that the above grate operates most satisfactorily when the angle of inclination of the refractory bed I0 is considerably greater than the angle of inclination of that portion of the bed constituting the grate bars. We have further found that extremely advantageous results have been obtained wherein the angle of inclination of that portion of the grate bed to the rear of the refractory bed, while being less than that of the refractory bed is still greater than that portion of the grate at the extreme rear of the furnace.

It is to be noted that the grate bars I practically lie on top of the refractory bed I0 so that they are exposed to the fuel on top of the same, and this transfers the heat of the water therein to the fuel to aid in evaporating the moisture contained in lthe fuel before it reaches the grate bars i4.

In operation, the fuel is deposited through the feed chute I9 upon the hearth section of the grate, which hearth section comprises the refractory material Il! as well as the tubular bars I. At this point, the fuel will be subjected to the heat of the furnace to sulch an extent that the fuel will be dried out, not only as the result of the heat which contacts the top of the material but also as the result of the radiant heat of the refractory material Iii. As the fuel is dried out, it becomes ignited and feeds forward onto the grate bars I4 where it continues to burn and develops its greatest heat. By the time the fuel has slid toward the back of the furnace, it will have been practically reduced to an ash which, of course, will be discharged in front of the bridge wall 3 by a dump plate orv other means. If, for any reason, the fuel at the rear end of the furnace, should become caked or fclinkered, or fail to feed forward, the pusher fingers lr6 may be manipulated for assisting in the forwardmovement of the fuel and also .to break up the fuel bed at this point.

Furthermore, it will lbe noted that, as above explained, with the transverse header 9 arranged eXteriorly of the furnace and connected to the water tubes .by detachable connection, this header may be removed without the necessity of entering the furnace proper.

We claim as our invention:

l. A furnace for burning refuse fuels and having a front wall and a bridge wall, including a grate comprising a hearth, downwardly inclined and extending from the intake end of the furnace toward the rear, a plurality of water tubes disposed side by side in spaced relation and eX- tending from front to rear of the furnace, the ends of the tubes extending through the front wall of lthe furnace, said tubes having their upper ends supported above the surface of said hearth and their lower ends supported adjacent the bridge wall, and grate bars mounted between said tubes beyond the hearth and having open- J lLio ings therethrough to permit the inlet of air beneath the fuel bed, the top surfaces of said grate bars being below the top surfaces of the tubes and the fuel being slidingly supported on the top surface of the tubes and leaving a space between the bottom surface of the fuel bed and the topsurface of the grate bars.

2. A furnace for burning refuse fuels and having a front wall and a bridge wall, including a grate comprising a hearth, downwardly inclined and extending from the intake end of the furnace toward the rear, a plurality of water tubes disposed side by side in spaced relation and eX- tending from front to rear of the furnace, the

Vends of said tubes projecting beyond the front of the furnace, a header connecting the ends of said tubes and detachably connected with said tubes, the upper ends of said tubes being supported above the surface of said hearth and their lower ends being supported adjacent the bridge wall, and .grate bars mounted between :said tubesbeyond the hearth and having openings therethrough permitting the inlet of air beneaththe fuel bed, the topI surfaces of said grate' bars being below the top surfaces of the tubes and slidingly supporting the fuel bed above the top surface of the grate 'bars to leave an air space between the bottom; of the fuel bed and the top surface of the grate bars.

3. A furnace for burning refuse fuels and having a front wall anda bridge wall, includinga grate comprising a hearth, downwardly inclined and extending from the 'intake end of the furnace toward the rear, a plurality of water tubes disposed side by side in spaced relation and eX- tending from the front to the rear of the furnace and having their upper ends associated with said hearth and their lower ends supported adjacent the bridge wall, and grate bars mounted `between said tubes beyond the hearth, and Va header ,arranged exteriorly of the furnace and connecting the upper ends of the furnace tubes.

VNICK T. PUCKETI'. MAURICE A. HOFFT. 

